1. Field of the Invention
The present invention relates to a method for measuring gears machined by an NC gear grinding machine and to a system which combines as a machine for grinding and forming gears using a grinding wheel and as a device for measuring the ground gears in-situ without detaching the same from the grinding machine.
2. Discussion of the Background
In the manufacture of high-precision gears that are machined by a gear grinding machine, it is a common practice to sample at least one gear in one production lot and check the tooth profile, trace, etc. to determine whether the machining conditions are appropriate before proceeding with the machining of the remaining gears in the lot.
Conventionally, precision inspection of gears in the gear grinding machine of this type has been conducted using a measurement device dedicated for this particular purpose. Attempts are now being made to develop a gear grinding machine which is capable of measuring the gears in-situ after completion of grinding to improve the efficiency, such as proposed, for example, by Japanese Utility Model Application Laid Open No. 92322/1989. According to this prior art, precision of tooth profile is checked while the ground gear is still attached to the work piece spindle of a gear generating/machining device. The gauge head of a measurement device which is fixed to the column plate is contacted with the tooth flank of said gear, which is caused to move in its movement of rolling in the basic circle by the rotation of the spindle and by the traverse of the spindle stock. The output signals of said measuring device are transmitted to a separate control device for data processing to check the precision.
The prior art method of inspecting the gear precision with a separate device is defective in that it takes time to transfer the workpiece or set the measurement conditions on the device. On the other hand, the gear grinding machine capable of measuring the gears is defective in that the types of gear that can be measured are limited, and in that it requires extra cost of adding mechanisms and devices such as for causing the ground gear to roll and for processing of the output signal data from the measurement device.